The purpose of the proposed Mentored Scientist Career Development Award (K01) is to provide the candidate with mentoring and research experiences that will promote his development as an independent researcher, with particular emphasis in operations and translational research of evidence based (EB) HIV prevention behavioral interventions among vulnerable populations. The objectives of the training are to develop knowledge and skills in: 1) qualitative and mixed methods research to understand the decision-making process among policy makers as it relates to HIV prevention policies; 2) expertise in operations research of EB HIV prevention intervention in international settings; 3) advanced methods for cost-effectiveness analysis; 4) theory-driven behavioral HIV prevention interventions among vulnerable populations and 5) additional training in the ethical conduct of research among vulnerable populations. Training activities will include didactic coursework and specific workshops, directed readings and one-on-one tutorials with mentors. The candidate will receive mentorship from a training committee comprised of internationally renowned experts in the fields of translational research, behavioral science, and mixed methods research at the University of California San Diego. The specific aims of the proposed research are to: 1) qualitatively describe policy makers' perspectives vis-`-vis institutional, political, cultural and individual factors that facilitate or impede the use of economic evaluation research in translating EB behavioral interventions into health policy; 2) To quantitatively characterize Mexican government and community based organizations (CBO) policy-makers' knowledge, attitudes and the experience of translating results from economic evaluation research into policy decisions; 3) To estimate the programmatic cost-effectiveness of the Mujer Segura behavioral intervention, shown to reduce HIV and sexually transmitted infections (STIs) among female sex workers (FSWs) in Mexico during the large scale implementation process compared to current Mexican HIV/STI prevention guidelines. The research aims will be accomplished by conducting a mixed methods research study. Quantitative data will be drawn from the operations costs and health outcomes of the upscale implementation of an efficacious intervention (Mujer Segura) among 960 FSWs in twelve different cities in Mexico (National Institute of Mental Health grant titled: Implementation of an efficacious intervention for Female Sex Workers in Mexico; R01MH08754; PI: Patterson; Co-I: Dr. Strathdee). Qualitative data will be collected from in-depth interviews of a sample of 40 policy makers from governmental institutions and CBOs involved in HIV prevention in Mexico. Findings from the proposed research will position the candidate to propose an R01 proposal for in depth study of HIV policy maker's decision making process in HIV translation. Moreover, the candidate's binational and ethnic minority background combined with the proposed training and research will support a career trajectory focused on vulnerable, underserved populations at risk for HIV infection.